Compensating means in barrel chamber for low and high powered cartridges



Oct. 23, 1962 w. E. ROSEBUSH OR L0 5 COMPENSATING Filed Feb. 25, 1961 x a a 6 M N fa z \1 Q 4/ Z i 5 m w mlvp/u 5 x 1; 7

IN VENTOR ATTORNEY United States Patent 3,059,367 COMPENSATING MEANS IN A BARREL CHAMBER FOR LOW AND HIGH POWERED CARTRIDGES Waldo E. Rosebush, Appleton, Wis.; F. Ward Rosebush and Judson G. Rosebush, Jr., executors of said Waldo E. Rosebush, deceased Filed Feb. 23, 1961, Ser. No. 90,985 2 Claims. (Cl. 42-76) This invention relates to a novel means of extremely simple construction whereby cartridges having cases or shells of different lengths and developing different recoil power may be employed in firearms having automatic recoil systems and without varying to any considerable extent the actual recoil force exerted on the breech by the two types of cartridges.

More particularly, it is an object of the present invention to provide means for accomplishing the aforedescribed result without the addition of any moving parts and with only a slight modification of the cartridge chamber, whereby ejection of the higher powered cartridge case will be retarded so that the recoil pressure actually exerted by the case on the breech bolt will be substantially equal to the pressure exerted by the case of the cartridge of lesser power, the ejection of which is not retarded.

More particularly, it is an aim of the present invention to provide a cartridge chamber which is modified in a manner to cause retarding of the ejection of a case of a higher powered cartridge due to expansion and deformation of the case and which means will not cause expansion of the case of a lesser powered cartridge to the same extent, whereby the recoil forces exerted by the two cartll'dgeCflSCS on thebreech bolt will be nearly equalized.

Various other objects and advantages of the invention will hereinafter become more fully apparent from the following description of the drawing, illustrating a pres- 1 L ently preferred embodiment thereof, and wherein:

FIGURE 1 is an enlarged fragmentary longitudinal sectional view of the rear portion of a firearm barrel and the forward portion of a breech bolt, with the barrel shown containing a cartridge with a long case;

FIGURE 2 is a view corresponding to FIGURE 1, but showing a cartridge having a short case contained within the barrel;

FIGURE 3 is a view corresponding to FIGURE 1, but showing the cartridge chamber empty;

FIGURE 4 is a side elevational view of the cartridge case as shown in FIGURE 1 as it will appear immediately after the cartridge is fired and before ejection of the cartridge case commences, and

FIGURE 5 is a cross sectional view through the barrel, taken substantially along a plane as indicated by the line 55 of FIGURE 3.

Referring more specifically to the drawing, the rear portion of a firearm barrel is shown in \FIGURES 1, 2 and 3, and is designated generally 6, and the forward portion of a breech bolt of the firearm is shown in conjunction therewith and is designated generally 7. The barrel 6 includes a rifled bore 8 and a cartridge chamber 9 which opens through the face 10 of the barrel 6. For the purpose of the description it can be assumed that the barrel 6 is of .22 caliber and that said barrel and the breech bolt 7 constitute parts of an automatic pistol; however, it is to be understood that the invention is not limited to firearms of a particular type or caliber.

The barrel 6 is shown in FIGURE 1 containing a conventional .22 caliber long rifle cartridge, designated generally 11, and in FIGURE 2, containing a conventional .22 caliber short cartridge 12.

The invention comprises a modification of the cartridge chamber 9 by forming therein a recess, designated generally 13. The recess 13 is shown as comprising an an- 3,959,367 Patented Oct. 23, 1962 "ice nular groove having a forward portion 14 which may constitute an annular rearwardly facing surface which is disposed at substantially a right angle to the axis of the barrel 6, but which is preferably rounded at the surface of the chamber 9, as seen at 14'. The recess or groove 13 has a rear portion 15 which is likewise annular and which slopes at a relatively slight angle with respect to the axis of the barrel 6 rearwardly from the shoulder 14 toward the surface of the chamber 9, so that the generally forwardly facing rear surface 15 is substantially rampshaped in cross section.

For the purpose of clarity, the diameter of the parts have been enlarged substantially in the drawing with respect to the actual diameters of a .22 caliber barrel, breech bolt and cartridges, and the size of the groove 13 has been exaggerated in relation to the bore 8 and chamber 9. Actually, the maximum diameter of the groove 13 is preferably about .237 inch.

As seen in FIGURE 1, the distance between the rearwardly facing forward shoulder '14 of the groove 13 and the face 10 of the barrel 6 is less than the distance between the annular front face 16 of the base 17 of the case or shell .18 of the cartridge 11 and the forward end or mouth -19 of the shell 18. Accordingly, when the shell 18 is seated in the chamber 9 with the base surface 16 thereof abutting the barrel face 10, the mouth 19 of the shell will be disposed forwardly of the groove 13 so that a portion of the shell covers the groove.

However, the spacing between the groove 13 and the faceltl is greater than the length of the shell 20 of the short cartridge 12, as measured between the forward face 21 of its base 22 and its forward end or mouth 23. Accordingly, when the shell or case 20 is seated in the chamber 9, as seen in FIGURE 2, the mouth 23 of the shell will be disposed rearwardly of the rearmost edge of the gr'oovel-S. Consequently, when the short cartridge 12 is fired and its bullet or projectile 24 is propelled from the 'mouth 23 by the propellant charge, not shown, contained within said shell 20, the shell 20 will be ejected rearwardly from the chamber 9 in a conventional manner to effect recoil of the breech bolt 7. Assuming that the conventional recoil mechanism, not shown, of the firearm is designed to function properly in response to the recoil force produced by the firing of the short cartridge 12 and which ejects the fired case 20 rearwardly from the chamber 9 to drive the breech bolt 7 rearwardly or from right to left, this recoil mechanism will not function properly with the higher powered cartridge -11 which exerts a much greater recoil force on the case 18 without the modification 13 of the chamber 9. Thus, by merely forming the recess 13 in the chamber 9 it is possible to fire either the low powered cartridge 12 or the higher powered cartridge 11 from the same firearm and with nearly the same recoil force being exerted against the breech bolt 7.

As is well-known, cartridge shells or cases are constructed to permit expansion thereof when the cartridge is fired to prevent escape of the expanding gases from the propellant charge rearwardly through the chamber around the case, and this occurs when the short cartridge 12 is fired. However, the shell or case 20, except for being expanded, is not otherwise deformed when the cartridge 12 is fired since it is unafiected by the groove or recess 13 which is disposed entirely in advance thereof, and the case 29 contracts after the gas pressure diminishes so that it can be ejected from the chamber 9 in a conventional manner.

However, when the long rifle cartridge 11, as shown in FIGURE 1, is fired to propel its projectile 25 through the bore 8, the gases initially generated by the explosive charge, not shown, within the shell 18, will not only expand the shell against the wall of the chamber 9 but will also defonn a part of the shell 18 into the recess or groove 13. Thus, immeditaely after the cartridge 11 is fired, the shell 18 will assume the shape as seen in FIGURE 4 having an annular enlargement 26 which nearly conforms in cross sectional shape to the groove 13 but which is not of sufi'icient size to fill the groove. As the pressure diminishes, the shell or case 18 will contract including the portion 26, and the shell will then beejected rearwardly' from the chamber 9 by the gas pressure, to propel the breechbolt 7 rearwardly to operate the automtaic recoil mechanism of the piece. The deformation 26 will retard ejectionof the shell 18 sufiiciently so that the force exerted thereby on the'breech bolt 7 will be approximately equal to the force exerted on the breech bolt by the shell 20. The annular rounded edge 14' will prevent shearing of the case when it is expanded into the groove 13. The case of a high velocity long rifle cartridge will be expanded to a greater extent to completely fill the groove 13 to thereby compensate for the greater recoil of its case. The groove or recess B -thus constitutes an automatic compensator whereby cartridges of diiferent power will exert approximately the same recoil thrust against the breech-bolt.

The inclined or ramp-shaped rear surface 15 of the recess 13 assists in flattening or contracting the deformation 26 'by functioning as a cam or wedge to assist in reducing the size of said deformation so that it can pass through the rearportion of the chamber 9. While slight variations may be made in the size of the groove 13 and in the shape of its rear surface 15,'tests have proven that even slight differences in said size and shape materially affect ejection of the long shell 18. A groove having a rear surface pitchedmore sharply than the rear surface '15 will not function eifectively'to contract the enlargement 26. If the maximum diameter of the groove 13 is increased even to .239 inch, ejection of the shell 18 becomes irregular, and if the groove diameter is increased to .245 inch, the fired case is not ejected and only a very slight movement of the breech bolt will occur. However, the power of-the charge contained in the cartridge can change the critical diameter of the groove .13 and/or the slope of the surface 15, and this could likewise apply to variationsincartridgecases aifecting the abilityof the case to expand and contract. Accordingly, it is not intended that the invention be limited to the exact size and shape of the recess 13 as hereindescribed, or to only one annular groove.

Various other modifications and changes are contemplated and may be resorted to, without departing from the "function or scope of the invention as hereinafter defined by the appended claims.

I claim as my invention:

1. A compensating means for an automatic recoil-type firearm comprising a firearm barrel having a cartridge chamber, a rear face through which the cartridge chamber opens, and asingle annular groove opening into said cartridge chamber and disposed relative to the rear face such that the groove is disposed forwardly of .the forward end of the case of a low powered cartridge seated in said chamber and rearwardly'of the forward end of a longer case of a higher powered cartridgeseated in said chamber whereby a part of the longer case is expanded into said groove, when the higher powered cartridge is fired, to retard ejection of said-longer case from the chamber, said groove comprising a sloping annular rear surface causing contraction of the expanded portion of the longer case during ejection thereof .and an annular radial front surface having a rounded edge merging with the surface of the cartridge chamber.

.2. A compenstaing means as in claim 1, said groove having a maximum diameter of approximately .012 inch greater than the outer diameter of the unfired cartridge case.

ReferencesCited in the file of this patent UNITED STATES PATENTS 290,738 Brown Dec. 25, 1883 1,103,202 Hoagland July 14, 1914 2,925,014 Abra-mson Feb. 16, 1960 FOREIGN PATENTS 8,943 G at ri ai 1915 

